This invention relates generally to imagewise stripping out portions of a member with a receiver sheet. Depending upon the temperature of the receiver sheet or the imaging member, i.e., donor, the positive or negative image may be stripped out. The above member may be fabricated by the process of migration imaging.
A migration imaging system capable of producing high quality images of high density, continuous tone and high resolution has been developed. Such imaging systems are disclosed in copending U.S. patent application Ser. No. 837,591, filed June 30, 1969, the entire contents of which are hereby incorporated herein by reference. In a typical embodiment of this migration imaging system, an imaging member comprising a substrate, a layer of softenable material containing electrically photosensitive migration material is latently imaged, e.g., by electrically charging the member and exposing the charged member to a pattern of activating electromagnetic radiation, such as light. Following exposure, the charged imaging member supports a pattern of electrostatic charge in imagewise configuration typically conforming a negative of the selective pattern of activating radiation to which the charge member was exposed. In the charge-expose mode of the preferred process, this selective pattern of charge on the imaging member is typically an electrostatic latent image. The exposed imaging member supporting the electrostatic latent image is then developed by softening the softenable layer at which time the previously charged photosensitive particles which have not been exposed to radiation, migrate in depth in the softenable layer as it is softened toward the substrate.
Various methods for developing, i.e., softening the softenable material to allow migration of the migration material, are known. These various development modes include solvent vapor softening, heat softening, combinations thereof as well as other methods for softening the softenable material to allow migration of the migration material in depth in the softenable material. The imaging system disclosed in copending U.S. application Ser. No. 837,591, filed June 30, 1969, the entire contents of which is hereby incorporated by reference herein, generally comprises a combination of process steps which include forming a latent image on a migration imaging member and developing with vapor or heat or combinations thereof to render the latent image visible.
Once a migration imaging member has been developed, i.e., the softenable material has been softened sufficiently to allow migration of the migration material in depth in the softenable material and the migration material has, in fact, migrated, then the fabrication of the member for utilization in the instant application is complete.
There has recently been discovered a process of stripping out either the positive or negative image, i.e., softenable material and migration material, from a member which contains areas of substantially the same density of migration material by the method of placing a receiver sheet against the member with sufficient heat and pressure to adhere the receiver sheet to the member and then separating the receiver sheet from the imaging member thereby stripping out portions of the softenable material. These portions being stripped contain substantially the same density of migration material. Depending upon the temperature of the receiver sheet or the imaging member, i.e., donor, a positive or negative image may be stripped from the member.
U.S. Pat. No. 3,664,834 is a pertinent patent which discloses an imaging member comprising a supporting substrate and an overlayer on the substrate. More particularly, the member comprises a soluble, electrically insulating binder layer containing particles dispersed in the soluble binder. The member is processed to substantially completely remove the soluble binder and form an image and a background pattern of particles on the substrate. This member is then contacted with a transfer member which is then stripped away whereby the image or the background pattern of migrated particles is selectively released to the transfer member. U.S. Pat. No. 3,664,834 is concerned with selective stripping between high concentration of particles and areas of less concentration of particles. U.S. Pat. No. 3,664,834 does not teach stripping as in the instant invention between different concentrations of migration particles dispersed in a softenable material, i.e., a binder configuration migration imaging member. Furthermore, U.S. Pat. No. 3,664,834 is concerned with wash-away developed members, i.e., where the softenable material and unmigrated migration material has been removed leaving only particles on the substrate. U.S. Pat. No. 3,664,834 is concerned with stripping away haze, i.e., residual particles in the unmigrated exposed areas, from the heavily migrated particles of migration material, i.e., the unexposed areas. Therefore, clearly U.S. Pat. No. 3,664,834 is concerned with selective particle strip-out and not the instant invention of selective binder strip-out which includes both softenable material and migration material.
The instant invention is concerned only with softening modes of development and U.S. Pat. No. 3,664,834 is concerned with wash-away development. The instant invention is concerned with stripping away particles contained in the original imaging member softenable material. In the instant invention the particles are stripped away and with them softenable material which has been undisturbed by development. As mentioned in U.S. Pat. No. 3,664,834, the softenable material has been essentially all removed by wash-away development whereas in the instant invention the softenable material is undisturbed by development.
Another pertinent patent in U.S. Pat. No. 3,741,757 which discloses an imaging member comprising a layer of softenable material and migration material selectively distributed in depth in the softenable material in first image configuration and comprising in addition to the first image pattern of migration material a background of substantial amounts of migration material in the softenable material but spaced apart in depth from the first image pattern and the process step of removing the background. U.S. Pat. No. 3,741,757 is concerned with splitting the softenable material on the average in a plane substantially between the image pattern configuration of the member and the background of the member thereby resulting in a positive and negative image. The background also may be abraded away. The instant invention is concerned with stripping out selective areas of a binder configuration member where the softenable material has not been disturbed by development.